U.S. patent application number 16/064754 was filed with the patent office on 2019-04-04 for method for transmitting or receiving signal in wireless communication system and apparatus therefor.
The applicant listed for this patent is LG Electronics Inc.. Invention is credited to Inkwon SEO, Yunjung YI.
Application Number | 20190103941 16/064754 |
Document ID | / |
Family ID | 63920296 |
Filed Date | 2019-04-04 |
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United States Patent
Application |
20190103941 |
Kind Code |
A1 |
SEO; Inkwon ; et
al. |
April 4, 2019 |
METHOD FOR TRANSMITTING OR RECEIVING SIGNAL IN WIRELESS
COMMUNICATION SYSTEM AND APPARATUS THEREFOR
Abstract
According to one embodiment of the present invention, a method
of receiving DCI by a UE includes receiving bundling information
regarding REGs via higher layer signaling, performing blind
detection for a PDCCH in a CORESET configured on a plurality of
OFDM symbols, and acquiring DCI from the PDCCH. When the bundling
information indicates a first value, the UE may perform bundling
such that only REGs locating on a same RB and corresponding to
different OFDM symbols in the CORESET, are bundled as 1 REG bundle,
and when the bundling information indicates a second value, the UE
may perform bundling such that the REGs locating on the same RB and
corresponding to the different OFDM symbols are bundled as 1 REG
bundle along with REGs locating on different RBs in the CORESET,
and the UE may perform the blind detection of the PDCCH by assuming
same precoding for REGs belonging to a same REG bundle as a result
of REG bundling.
Inventors: |
SEO; Inkwon; (Seoul, KR)
; YI; Yunjung; (Seoul, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
LG Electronics Inc. |
Seoul |
|
KR |
|
|
Family ID: |
63920296 |
Appl. No.: |
16/064754 |
Filed: |
April 24, 2018 |
PCT Filed: |
April 24, 2018 |
PCT NO: |
PCT/KR2018/004725 |
371 Date: |
June 21, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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62489419 |
Apr 24, 2017 |
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62519157 |
Jun 13, 2017 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04L 5/00 20130101; H04L
25/0224 20130101; H04W 72/042 20130101; H04L 1/0072 20130101; H04L
25/0202 20130101; H04L 1/0009 20130101; H04L 5/0007 20130101; H04L
5/0053 20130101; H04L 1/0038 20130101; H04L 1/0046 20130101; H04L
1/00 20130101; H04L 1/0071 20130101; H04L 5/0094 20130101 |
International
Class: |
H04L 1/00 20060101
H04L001/00; H04L 5/00 20060101 H04L005/00; H04W 72/04 20060101
H04W072/04; H04L 25/02 20060101 H04L025/02 |
Claims
1-15. (canceled)
16. A method of decoding a physical downlink control channel
(PDCCH) by a user equipment (UE) in a wireless communication
system, the method comprising: receiving bundle size information
related to a bundle size of resource element groups (REGs) over
which same precoding is applied, each REG occupying 1 resource
block (RB) in a frequency domain during 1 orthogonal frequency
divisional multiplexing (OFDM) symbol in a time domain; and
decoding the PDCCH over a control resource set (CORESET) configured
with a plurality of REG bundles in a CORESET duration that spans a
plurality of OFDM symbols in the time domain, based on REGs in each
REG bundle having been precoded with the same precoding, wherein
the plurality of REG bundles in the CORESET are mapped to control
channel elements (CCEs) by an interleaving, with each CCE
comprising 6 REGs, and wherein, in a state in which the bundle size
of REGs indicated by the bundle size information is a first bundle
size, the first bundle size is equal to a number of the plurality
of OFDM symbols that configure the CORESET duration.
17. The method of claim 16, wherein in the state in which the
bundle size of the REGs is the first bundle size, only REGs that
occupy a same RB in the frequency domain and different OFDM symbols
in the time domain are bundled as one REG bundle.
18. The method of claim 16, wherein in a state in which the bundle
size of the REGs is a second bundle size different from the first
bundle size, the second bundle size is equal to an integer multiple
of the number of the plurality of OFDM symbols that configure the
CORESET duration.
19. The method of claim 18, wherein in the state in which the
bundle size of the REGs is the second bundle size, REGs that occupy
different RBs in the frequency domain and different OFDM symbols in
the time domain are bundled as one REG bundle.
20. The method of claim 18, wherein in the state in which the
bundle size of the REGs is the second bundle size, the second
bundle size is equal to 6.
21. The method of claim 16, wherein a plurality of CORESETs
comprising the CORESET are configured for the UE, and wherein the
method further comprises: receiving, for each of the plurality of
CORESETs, a corresponding bundle size information for REGs in the
CORESET; and decoding, for each of the plurality of CORESETs, the
PDCCH over the CORESET.
22. The method of claim 16, wherein the plurality of REG bundles in
the CORESET are mapped to the CCEs by the interleaving in units of
REG bundles based on an REG bundle index.
23. The method of claim 16, further comprising obtaining downlink
control information (DCI) from the decoded PDCCH.
24. The method of claim 16, wherein the number of the plurality of
OFDM symbols that configure the CORESET duration is equal to 2 or
3.
25. A method of encoding a physical downlink control channel
(PDCCH) by a base station (BS) in a wireless communication system,
the method comprising: transmitting bundle size information related
to a bundle size of resource element groups (REGs) over which same
precoding is applied, each REG occupying 1 resource block (RB) in a
frequency domain during 1 orthogonal frequency divisional
multiplexing (OFDM) symbol in a time domain; and encoding the PDCCH
over a control resource set (CORESET) configured with a plurality
of REG bundles in a CORESET duration that spans a plurality of OFDM
symbols in the time domain, based on precoding REGs in each REG
bundle with the same precoding, wherein the plurality of REG
bundles in the CORESET are mapped to control channel elements
(CCEs) by an interleaving, with each CCE comprising 6 REGs, and
wherein, in a state in which the bundle size of REGs indicated by
the bundle size information is a first bundle size, the first
bundle size is equal to a number of the plurality of OFDM symbols
that configure the CORESET duration.
26. The method of claim 25, wherein in the state in which the
bundle size of the REGs is the first bundle size, only REGs that
occupy a same RB in the frequency domain and different OFDM symbols
in the time domain are bundled as one REG bundle.
27. The method of claim 25, wherein in a state in which the bundle
size of the REGs is a second bundle size different from the first
bundle size, the second bundle size is equal to an integer multiple
of the number of the plurality of OFDM symbols that configure the
CORESET duration.
28. The method of claim 27, wherein in the state in which the
bundle size of the REGs is the second bundle size, REGs that occupy
different RBs in the frequency domain and different OFDM symbols in
the time domain are bundled as one REG bundle.
29. The method of claim 27, wherein in the state in which the
bundle size of the REGs is the second bundle size, the second
bundle size is equal to 6.
30. The method of claim 25, wherein a plurality of CORESETs
comprising the CORESET are configured, and wherein the method
further comprises: transmitting, for each of the plurality of
CORESETs, a corresponding bundle size information for REGs in the
CORESET; and encoding, for each of the plurality of CORESETs, the
PDCCH over the CORESET.
31. The method of claim 25, wherein the plurality of REG bundles in
the CORESET are mapped to the CCEs by the interleaving in units of
REG bundles based on an REG bundle index.
32. The method of claim 25, further comprising transmitting
downlink control information (DCI) through the PDCCH.
33. The method of claim 25, wherein the number of the plurality of
OFDM symbols that configure the CORESET duration is equal to 2 or
3.
34. A user equipment (UE) configured to decode a physical downlink
control channel (PDCCH) in a wireless communication system, the UE
comprising: a radio-frequency (RF) module; at least one processor;
and at least one computer memory operably connectable to the at
least one processor and storing instructions that, when executed,
causes the at least one processor to perform operations that
comprise: receiving, through the RF module, bundle size information
related to a bundle size of resource element groups (REGs) over
which same precoding is applied, each REG occupying 1 resource
block (RB) in a frequency domain during 1 orthogonal frequency
divisional multiplexing (OFDM) symbol in a time domain; and
decoding the PDCCH over a control resource set (CORESET) configured
with a plurality of REG bundles in a CORESET duration that spans a
plurality of OFDM symbols in the time domain, based on REGs in each
REG bundle having been precoded with the same precoding, wherein
the plurality of REG bundles in the CORESET are mapped to control
channel elements (CCEs) by an interleaving, with each CCE
comprising 6 REGs, and wherein, in a state in which the bundle size
of REGs indicated by the bundle size information is a first bundle
size, the first bundle size is equal to a number of the plurality
of OFDM symbols that configure the CORESET duration.
35. (canceled)
Description
TECHNICAL FIELD
[0001] The present invention relates to a wireless communication
system, and more particularly, to a method and apparatus for
transmitting and receiving a downlink (DL) control information in a
wireless communication system.
BACKGROUND ART
[0002] First, the existing 3GPP LTE/LTE-A system will be briefly
described. Referring to FIG. 1, the UE performs an initial cell
search (S101). In the initial cell search process, the UE receives
a Primary Synchronization Channel (P-SCH) and a Secondary
Synchronization Channel (S-SCH) from a base station, performs
downlink synchronization with the BS, and acquires information such
as a cell ID. Thereafter, the UE acquires system information (e.g.,
MIB) through a PBCH (Physical Broadcast Channel). The UE can
receive the DL RS (Downlink Reference Signal) and check the
downlink channel status.
[0003] After the initial cell search, the UE can acquire more
detailed system information (e.g., SIBs) by receiving a Physical
Downlink Control Channel (PDCCH) and a Physical Downlink Control
Channel (PDSCH) scheduled by the PDCCH (S102).
[0004] The UE may perform a random access procedure for uplink
synchronization. The UE transmits a preamble (e.g., Msg1) through a
physical random access channel (PRACH) (S103), and receives a
response message (e.g., Msg2) for the preamble through PDCCH and
PDSCH corresponding to the PDCCH. In the case of a contention-based
random access, a contention resolution procedure such as additional
PRACH transmission (S105) and PDCCH/PDSCH reception (S106) may be
performed.
[0005] Then, the UE can perform PDCCH/PDSCH reception (S107) and
Physical Uplink Shared Channel (PUSCH)/Physical Uplink Control
Channel (PUCCH) transmission (S108) as a general uplink/downlink
signal transmission procedure. The UE can transmit UCI (Uplink
Control Information) to the BS. The UCI may include HARQ ACK/NACK
(Hybrid Automatic Repeat reQuest Acknowledgment/Negative ACK), SR
(Scheduling Request), CQI (Channel Quality Indicator), PMI
(Precoding Matrix Indicator) and/or RI etc.
DISCLOSURE
Technical Problem
[0006] An object of the present invention devised to solve the
problem lies in a method and apparatus for more effectively and
accurately transmitting or receiving downlink control information
through resource element group (REG) bundling in wireless
communication system.
[0007] It is to be understood that both the foregoing general
description and the following detailed description of the present
invention are exemplary and explanatory and are intended to provide
further explanation of the invention as claimed.
Technical Solution
[0008] In an aspect of the present invention to achieve the object
of the present invention, a method of receiving downlink control
information by a user equipment (UE) in a wireless communication
system, includes receiving, via higher layer signaling, bundling
information regarding resource element groups (REGs), each of the
REGs corresponding to 1 resource block (RB) and 1 orthogonal
frequency divisional multiplexing (OFDM) symbol; performing blind
detection for a physical downlink control channel (PDCCH) in a
control resource set (CORESET) configured on a plurality of OFDM
symbols; and acquiring downlink control information (DCI) from the
blind-detected PDCCH, wherein in the blind detection for the PDCCH,
when the bundling information indicates a first value, the UE may
perform bundling such that only REGs locating on a same RB and
corresponding to different OFDM symbols in the CORESET, are bundled
as 1 REG bundle, and when the bundling information indicates a
second value, the UE may perform bundling such that the REGs
locating on the same RB and corresponding to the different OFDM
symbols are bundled as 1 REG bundle along with REGs locating on
different RBs in the CORESET, and wherein the UE may perform the
blind detection of the PDCCH by assuming same precoding for REGs
which belong to a same REG bundle as a result of REG bundling.
[0009] In other aspect of the present invention, a method of
transmitting downlink control information by a base station (BS) in
a wireless communication system, includes transmitting, via higher
layer signaling, bundling information regarding resource element
groups (REGs), each of the REGs corresponding to 1 resource block
(RB) and 1 orthogonal frequency divisional multiplexing (OFDM)
symbol; and transmitting downlink control information (DCI) through
a physical downlink control channel (PDCCH) in a control resource
set (CORESET) configured on a plurality of OFDM symbols, wherein in
transmitting the DCI, when the bundling information indicates a
first value, the BS may perform bundling such that only REGs
locating on a same RB and corresponding to different OFDM symbols
in the CORESET, are bundled as 1 REG bundle, when the bundling
information indicates a second value, the BS may perform bundling
such that the REGs locating on the same RB and corresponding to the
different OFDM symbols are bundled as 1 REG bundle along with REGs
locating on different RBs in the CORESET, and wherein the BS may
transmit the DCI by applying same precoding for REGs belonging to a
same REG bundle as a result of REG bundling.
[0010] In another aspect of the present invention, a user equipment
(UE) for receiving downlink control information, includes a
receiver; and a processor to receive, via higher layer signaling by
using the receiver, bundling information regarding resource element
groups (REGs), each of the REGs corresponding to 1 resource block
(RB) and 1 orthogonal frequency divisional multiplexing (OFDM)
symbol, to perform blind detection for a physical downlink control
channel (PDCCH) in a control resource set (CORESET) configured on a
plurality of OFDM symbols, and to acquire downlink control
information (DCI) from the blind-detected PDCCH, wherein in the
blind detection for the PDCCH, when the bundling information
indicates a first value, the processor may perform bundling such
that only REGs locating on a same RB and corresponding to different
OFDM symbols in the CORESET, are bundled as 1 REG bundle, and when
the bundling information indicates a second value, the processor
may perform bundling such that the REGs locating on the same RB and
corresponding to the different OFDM symbols are bundled as 1 REG
bundle along with REGs locating on different RBs in the CORESET,
and wherein the processor may perform the blind detection of the
PDCCH by assuming same precoding for REGs which belong to a same
REG bundle as a result of REG bundling.
[0011] In another aspect of the present invention, a base station
(BS) for transmitting downlink control information, includes a
transmitter; and a processor to transmit, via higher layer
signaling by using the transceiver, bundling information regarding
resource element groups (REGs), each of the REGs corresponding to 1
resource block (RB) and 1 orthogonal frequency divisional
multiplexing (OFDM) symbol, and to transmit downlink control
information (DCI) through a physical downlink control channel
(PDCCH) in a control resource set (CORESET) configured on a
plurality of OFDM symbols, wherein in the transmission of the DCI,
when the bundling information indicates a first value, the
processor may perform bundling such that only REGs locating on a
same RB and corresponding to different OFDM symbols in the CORESET,
are bundled as 1 REG bundle, when the bundling information
indicates a second value, the processor may perform bundling such
that the REGs locating on the same RB and corresponding to the
different OFDM symbols are bundled as 1 REG bundle along with REGs
locating on different RBs in the CORESET, and wherein the processor
may transmit the DCI by applying same precoding for REGs belonging
to a same REG bundle as a result of REG bundling.
[0012] When the bundling information indicates the first value, 1
REG bundle size may be configured to be the same as the number of
the plurality of OFDM symbols for configuring the CORESET.
[0013] When the bundling information indicates the second value, 1
REG bundle size may be configured to be the same as the number of
REGs included in 1 control channel element (CCE).
[0014] One or more CORESETs including the CORESET may be configured
in the UE. The bundling information and a control channel element
(CCE)-to-REG mapping type may be indicated for each of the one or
more CORESETs.
[0015] The bundling information may include bundle size information
indicating the number of REGs included in 1 REG bundle.
[0016] The control channel element (CCE)-to-REG mapping type of the
CORESET may be configured as an interleaved mapping type among a
localized mapping type and the interleaved mapping type.
[0017] Interleaving for the CCE-to-REG mapping may be performed in
a unit of a REG bundle using an REG bundle index.
[0018] A supported bundle size may be differently determined
according to the CCE-to-REG mapping type.
[0019] The bundling information may include at least one of
intra-CCE bundle size information for bundling of REGs belonging to
the same control channel element (CCE) and inter-CCE bundle size
information for bundling of REGs belonging to different control
channel elements (CCEs). When the bundling information includes the
inter-CCE bundle size information, the UE may perform blind
detection for the PDCCH by assuming the same precoding for REGs of
different CCEs belonging to the same inter-CCE bundle.
[0020] When the bundling information indicates the first value, the
UE may perform time domain REG bundling and, when the bundling
information indicates the second value, the UE may perform
time-frequency domain REG bundling.
[0021] The number of the plurality of OFDM symbols for configuring
the CORESET may be 2 or 3.
[0022] The UE may perform demodulation for the PDCCH by assuming
that the same precoding is applied to reference signals received
through REGs belonging to the same REG bundle.
Advantageous Effects
[0023] According to an embodiment of the present invention, a user
equipment (UE) performs time domain bundling or time-frequency
domain bundling according to indication of a network and assumes
the same precoding with respect to a plurality of resource element
groups (REGs) belonging to 1 REG bundle and, thus, detection for a
physical downlink control channel (PDCCH) carrying downlink control
information (DCI) may be more accurately and effectively
performed.
[0024] It will be appreciated by persons skilled in the art that
that the effects that could be achieved with the present invention
are not limited to what has been particularly described hereinabove
and other advantages of the present invention will be more clearly
understood from the following detailed description taken in
conjunction with the accompanying drawings.
DESCRIPTION OF DRAWINGS
[0025] FIG. 1 illustrates physical channels used in a 3GPP
LTE/LTE-A system and a general signal transmission method using the
physical channels.
[0026] FIG. 2 illustrates an NR control region according to an
embodiment of the present invention.
[0027] FIG. 3 illustrates frequency domain bundling according to an
embodiment of the present invention.
[0028] FIG. 4 illustrates a time domain bundling type according to
an embodiment of the present invention.
[0029] FIG. 5 illustrates channel estimation performance of time
domain bundling according to an embodiment of the present
invention.
[0030] FIG. 6 illustrates bundling options according to an
embodiment of the present invention.
[0031] FIG. 7 illustrates a CORESET and a sub-CORESET according to
an embodiment of the present invention.
[0032] FIG. 8 is a diagram for explanation of resource indexing
according to an embodiment of the present invention.
[0033] FIG. 9 is a diagram for explanation of a method of
indicating the same precoding pattern according to an embodiment of
the present invention.
[0034] FIG. 10 illustrates RS patterns for adjusting RS patterns
for adjusting RS density according to an embodiment of the present
invention.
[0035] FIG. 11 illustrates the case in which CORESETs with
different CORESET durations overlap with each other according to an
embodiment of the present invention.
[0036] FIG. 12 illustrates a flow of a method of transmitting and
receiving downlink control information (DCI) according to an
embodiment of the present invention.
[0037] FIG. 13 illustrates a base station (BS) and a user equipment
(UE) according to an embodiment of the present invention.
MODE FOR INVENTION
[0038] The following description of embodiments of the present
invention may apply to various wireless access systems including
CDMA (code division multiple access), FDMA (frequency division
multiple access), TDMA (time division multiple access), OFDMA
(orthogonal frequency division multiple access), SC-FDMA (single
carrier frequency division multiple access) and the like. CDMA can
be implemented with such a radio technology as UTRA (universal
terrestrial radio access), CDMA 2000 and the like. TDMA can be
implemented with such a radio technology as GSM/GPRS/EDGE (Global
System for Mobile communications)/General Packet Radio
Service/Enhanced Data Rates for GSM Evolution). OFDMA can be
implemented with such a radio technology as IEEE 802.11 (Wi-Fi),
IEEE 802.16 (WiMAX), IEEE 802.20, E-UTRA (Evolved UTRA), etc. UTRA
is a part of UMTS (Universal Mobile Telecommunications System).
3GPP (3rd Generation Partnership Project) LTE (long term evolution)
is a part of E-UMTS (Evolved UMTS) that uses E-UTRA. 3GPP LTE
adopts OFDMA in downlink and adopts SC-FDMA in uplink. LTE-A
(LTE-Advanced) is an evolved version of 3GPP LTE.
[0039] For clarity, the following description mainly concerns 3GPP
LTE system or 3GPP LTE-A system, by which the technical idea of the
present invention may be non-limited. Specific terminologies used
in the following description are provided to help understand the
present invention and the use of the terminologies can be modified
to a different form within a scope of the technical idea of the
present invention.
[0040] As many as possible communication devices have demanded as
high as communication capacity and, thus, there has been a need for
enhanced mobile broadband (eMBB) communication compared with legacy
radio access technology (RAT) in a recently discussed
next-generation communication system. In addition, massive machine
type communications (mMTC) for connecting a plurality of devices
and objects to provide various services anytime and anywhere is
also one of factors to be considered in next-generation
communication. In addition, in consideration of a service/UE that
is sensitive to reliability and latency, ultra-reliable and low
latency communication (URLLC) has been discussed for a
next-generation communication system.
[0041] As such, new RAT that considers eMBB, mMTC, URLCC, and so on
has been discussed for next-generation wireless communication.
[0042] Some LTE/LTE-A operations and configuration that are not at
variance to a design of New RAT may also be applied to new RAT. For
convenience, new RAT may be referred to as 5G mobile
communication.
[0043] <NR Frame Structure and Physical Resource>
[0044] In an NR system, downlink (DL) and downlink (UL)
transmission may be performed through frames having duration of 10
ms and each frame may include 10 subframes. Accordingly, 1 subframe
may correspond to 1 ms. Each frame may be divided into two
half-frames.
[0045] 1 subframe may include
N.sub.symb.sup.subframe,.mu.=N.sub.symb.sup.slot.times.N.sub.slot.sup.sub-
frame,.mu. contiguous OFDM symbols. N.sub.symb.sup.slot represents
the number of symbols per slot, .mu. represents OFDM numerology,
and N.sub.slot.sup.subframe,.mu. represents the number of slots per
subframe with respect to corresponding .mu.. In NR, multiple OFDM
numerologies shown in Table 1 below may be supported.
TABLE-US-00001 TABLE 1 .mu. .DELTA.f = 2.sup..mu. 15[kHz] Cyclic
prefix 0 15 Normal 1 30 Normal 2 60 Normal, Extended 3 120 Normal 4
240 Normal
[0046] In Table 1 above, .DELTA.f refers to subcarrier spacing
(SCS). .mu. and cyclic prefix with respect to a DL carrier
bandwidth part (BWP) and .mu. and cyclic prefix with respect to a
UL carrier BWP may be configured for a UE via UL signaling.
[0047] Table 2 below shows the number of N.sub.symb.sup.slot of
symbols per slot, the number N.sub.slot.sup.frame,.mu. of symbols
per frame, and the number N.sub.slot.sup.subframe,.mu. of slots per
subframe with respect to each SCS in the case of normal CP.
TABLE-US-00002 TABLE 2 .mu. N.sub.symb.sup.slot
N.sub.slot.sup.frame, .mu. N.sub.slot.sup.subframe, .mu. 0 14 10 1
1 14 20 2 2 14 40 4 3 14 80 8 4 14 160 16 5 14 320 32
[0048] Table 3 below shows the number N.sub.symb.sup.slot of
symbols per slot, the number N.sub.slot.sup.frame,.mu. of slots per
frame, and the number N.sub.slot.sup.subframe,.mu. of slots per
subframe with respect to each SCS in the ca se of extended CP.
TABLE-US-00003 TABLE 3 .mu. N.sub.symb.sup.slot
N.sub.slot.sup.frame, .mu. N.sub.slot.sup.subframe, .mu. 2 12 40
4
[0049] As such, in an NR system, the number of slots included in 1
subframe may be changed according to subcarrier spacing (SCS). OFDM
symbols included in each slot may correspond to any one of D (DL),
U (UL), and X (flexible). DL transmission may be performed in a D
or X symbol and UL transmission may be performed in a U or X
symbol. A Flexible resource (e.g., X symbol) may also be referred
to as a Reserved resource, an Other resource, or a Unknown
resource.
[0050] In NR, one resource block (RB) may correspond to 12
subcarriers in the frequency domain. A RB may include a plurality
of OFDM symbols. A resource element (RE) may correspond to 1
subcarrier and 1 OFDM symbol. Accordingly, 12 REs may be present on
1 OFDM symbol in 1 RB.
[0051] A carrier BWP may be defined as a set of contiguous physical
resource blocks (PRBs). The carrier BWP may also be simply referred
to a BWP. A maximum of 4 BWPs may be configured for each of UL/DL
link in 1 UE. Even if multiple BWPs are configured, 1 BWP may be
activated for a given time period. However, when a supplementary
uplink (SUL) is configured in a UE, 4 BWPs may be additionally
configured for the SUL and 1 BWP may be activated for a given time
period. A UE may not be expected to receive a PDSCH, a PDCCH, a
channel state information-reference signal (CSI-RS), or a tracking
reference signal (TRS) out of the activated DL BWP. In addition,
the UE may not be expected to receive a PUSCH or a PUCCH out of the
activated UL BWP.
[0052] <NR DL Control Channel>
[0053] In an NR system, a transmissions NR system, a transmission
unit of a control channel may be defined as a resource element
group (REG) and/or a control channel element (CCE), etc. The CCE
may refer to a minimum unit for control channel transmission. That
is, a minimum PDCCH size may correspond to 1 CCE. When an
aggregation level is equal to or greater than 2, a network may
group a plurality of CCEs to transmit one PDCCH (i.e., CCE
aggregation).
[0054] An REG may correspond to 1 OFDM symbol in the time domain
and may correspond to 1 PRB in the frequency domain. In addition, 1
CCE may correspond to 6 REGs.
[0055] A control resource set (CORESET) and a search space (SS) are
briefly described now. The CORESET may be a set of resources for
control signal transmission and the search space may be aggregation
of control channel candidates for perform blind detection. The
search space may be configured for the CORESET. For example, when
one search space is defined on one CORESET, a CORESET for a common
search space (CSS) and a CORESET for a UE-specific search space
(USS) may each be configured. As another example, a plurality of
search spaces may be defined in one CORESET. For example, the CSS
and the USS may be configured for the same CORESET. In the
following example, the CSS may refer to a CORESET with a CSS
configured therefor and the USS may refer to a CORESET with a USS
configured therefor, or the like.
[0056] An eNB may signal information on a CORESET to a UE. For
example, a CORESET configuration for each CORESET may be signaled
to the UE, and the CORESET configuration may be signaled in time
duration (e.g., 1/2/3 symbol), etc. of the corresponding CORESET.
Information included in the CORESET configuration is described
below in detail.
[0057] <Bundling for NR-PDCCH>
[0058] Prior to a description of resource bundling in an NR system,
physical resource block (PRB) bundling in a legacy LTE system is
described briefly. When a DMRS with lower density than a cell
specific RS (CRS) is used in an LTE system, an available resource
is increased for data transmission but, as the number of available
RSs for channel estimation is increased, channel estimation
performance may be degraded. As such, to minimize degradation in
channel estimation performance during DMRS use, PRB bundling is
introduced in an LTE system. For ex ample, to ensure channel
estimation performance in a transmission mode in which a DMRS is
used, sections in which the same precoding is applied may be
defined as a PRB bundle and, in the corresponding sections, a UE
may perform channel estimation using RSs belonging to different
PRBs. For example, DMRS 2 mapped to PRB 2 as well as DMRS 1 mapped
to PRB 1 may be used for channel estimation of demodulation of data
mapped to PRB 1. For valid channel estimation in units of PRB
bundles, the same precoding needs to be applied to DMRS 1 and DMRS
2.
[0059] To enhance system flexibility in NR, reduction in use of a
common RS has been discussed. The common RS may be a cell-commonly
transmitted RS and may refer to an always on RS that is not capable
of being on/off UE-specifically. For example, a cell-specific RS
(CRS) of an LTE system may be an example of the common RS.
[0060] A design for reduction in the common RS is also applied to a
control channel (e.g., PDCCH) of NR and, thus, it may be desirable
to perform bundling between different control channel resources to
enhance channel estimation performance of a control channel.
[0061] Hereinafter, it is assumed that 1 REG=1 PRB & 1 OFDM
symbol, and 1 CCE=6 REGs but the present invention is not limited
thereto and the present invention may also be applied to the case
in which various resource units, e.g., REG, CCE, and PDCCH
candidate are configured using different methods. As another
example of definition of an REG, 1 REG may correspond to 12
contiguous resource elements (REs) in the frequency domain and the
number of REs used for control information transmission may be
changed according to whether an RS is included in the corresponding
REG and/or whether a reserved resource is present.
[0062] Hereinafter, the RS may include an RS for demodulation of a
control channel, an RS for positioning, CSI-RS for CSI feedback, an
interference measurement resource (IMR), a cell-specific tracking
RS (e.g., phase tracking), a radio link monitoring (RLM)-RS, and/or
radio resource management (RRM)-RS, etc. and for convenience of
description, the present invention is mainly described in terms of
an RS for demodulation of a control channel.
[0063] FIG. 2 illustrates a NR control region according to an
embodiment of the present invention.
[0064] A CORESET may correspond to a region in which REG/CCE
indexing is performed. 1 UE may be configured with one or more
CORESETs from a network. When a plurality of CORESETs is configured
for 1 UE, the respective CORESETs may have different properties.
For example, a CCE-to-REG mapping type, a PDCCH-to-CCE mapping
type, and/or an RS configuration, etc. for each CORESET may be
defined via high layer signaling (e.g., CORESET configuration).
[0065] Although FIG. 2 illustrates only CORESET duration in the
time domain, a range of a CORESET may also be configured in the
frequency domain.
[0066] Bundling of an REG level may be applied to an NR control
channel. When the bundling of an REG level is applied, the same
precoding may be applied to different REGs belonging to the same
bundle.
[0067] When different REGs belonging to the same bundle belongs to
1 CCE, such REG bundling may be defined as intra-CCE REG bundling.
When different REGs belonging to the same bundle belongs to
different CCEs, such REG bundling may be defined as inter-CCE
bundling.
[0068] Hereinafter, a method of performing bundling on an NR
control channel is proposed. In the following examples, 1 CCE=6
REGs is assumed but the present invention may also be applied to
the case in which the number of REGs per CCE may be differently
defined.
[0069] REG bundling in an NR control channel may be defined in the
frequency domain and/or the time domain. An operating method, etc.
of a UE and an eNB for bundling in each domain is described
below.
[0070] Frequency Domain Bundling
[0071] In terms of a network, frequency domain REG bundling may
apply the same precoding to different REGs on the same time
instance. A UE may perform channel estimation using RSs on
different REGs belonging to the same bundle, thereby enhancing
channel estimation performance.
[0072] FIG. 3 illustrates an example of frequency domain
bundling.
[0073] R refers to an RE in which a reference signal is
transmitted, D refers to an RE in which control information is
transmitted, and X refers to an RE in which an RS of another
antenna port is transmitted.
[0074] When a bundle size is 1 REG (i.e., when REG bundling is not
applied), channel estimation for each RE in which control
information is transmitted may be performed using an RS in a
corresponding REG. When a bundle size is 2 REGs, channel estimation
for each RE in which control information is transmitted may be
performed using all RS(s) present in the bundle size.
[0075] Accordingly, when a bundle size is greater than 1 REG, a UE
may perform channel estimation using as many as possible RS(s) to
enhance channel estimation performance.
[0076] In the case of frequency domain bundling, it may be
desirable to differently configure a size of bundling according to
a resource mapping type of a CORESET in which bundling is
performed. For example, when a CCE-to-REG mapping method indicted
through a CORESET configuration is distributed mapping (e.g.,
interleaving), a bundle size may be determined in consideration of
both channel estimation performance and frequency diversity gain.
When the frequency diversity gain determines overall performance
compared with the channel estimation performance, it may be
desirable not to perform bundling for enhancing the channel
estimation performance or maintain a bundle size in a small value
(e.g., 2 REGs). On the other hand, when the channel estimation
performance is more important than acquisition of the frequency
diversity gain, it may be desirable to configure the bundle size as
a large value (e.g., 3 REGs) to enhance the channel estimation
performance.
[0077] As such, to adaptively correspond to various channel
environments, a network may configure a bundle size for each
specific resource region (e.g., CORESET). For example, an REG
bundle size for each CORESET may be indicated to a UE via higher
layer signaling (e.g., CORESET configuration), etc.
[0078] In the case of localized mapping, it may be desirable to
support a large bundle size (e.g., maximum REG bundle size). The
bundle size of the localized mapping may be more largely configured
than a bundle size of the distributed mapping.
[0079] Use of the localized mapping may mean that a network applies
appropriate precoding to a UE due to relatively accurate channel
information between the network and the UE. In this case, the
network may deploy all REGs configuring a CCE to be adjacent to
each other in the frequency domain and may apply the same precoding
to REGs. For example, in the case of non-Interleaved (i.e.
localized) CCE-to-REG mapping, 1 CCE may correspond to an REG
bundle. In other words, an REG bundle size may also be fixed to 1
CCE (i.e., 6 REGs) during localized mapping.
[0080] According to an embodiment of the present invention,
signaling of different bundle sizes according to a resource mapping
type (i.e., REG-to-CCE mapping type) by a network with respect to
frequency domain bundling is proposed. A supported bundle size may
be determined according to an REG-to-CCE mapping type. For example,
in localized mapping, an REG bundle size may be fixed to 6-REG and,
in distributed mapping (e.g., interleaving), a network may
configure an REG bundle size for a UE via higher layer signaling
(e.g., CORESET configuration).
[0081] Signaling of different bundle sizes according to a resource
mapping type by a network may mean that a maximum value of a bundle
size for each resource mapping type (e.g., localized/distributed
mapping) is differently configured. For example, when the number of
bits for signaling a bundle size is equalized in both
localized/distributed mappings (e.g., when the number of available
bundle sizes is constant irrespective of a resource mapping type),
a bundle size indicated by a corresponding bit value may be
differently defined according to a resource mapping method. For
example, assuming that a bundle size is indicated by 1 bit, 1
Bit=0/1 may represent bundle size=2/3 REGs in the distributed
mapping, and 1 Bit=0/1 may represent bundle size=3/6 REGs in the
localized mapping.
[0082] Another bundle size may also be defined for inter-CCE
bundling. For example, the aforementioned bundle size may refer to
an intra-CCE bundle size, and a maximum bundle size may be
additionally defined for inter-CCE bundling separately from an
intra-CCE bundle size. When REGs belonging to different CCEs are
positioned adjacently to each other, a network may perform
frequency domain bundling on REGs positioned in a maximum bundle
size. As such, a maximum bundling size for the inter-CCE bundling
may refer to a distance between REGs in which the inter-CCE
bundling is permissible. For example, the maximum bundling size may
be defined on the frequency domain. For example, the maximum
bundling size may be defined on the frequency domain and/or the
time domain.
[0083] A first bundle size for the intra-CCE bundling and a second
bundle size for the inter-CCE bundling may be independently
signaled. A network/UE may perform REG indexing/CCE indexing, etc.
based on a first bundle size or the like in the intra-CCE bundling
and may perform the inter-CCE bundling on REGs belonging to
different CCEs in the second bundle size after CCE aggregation. The
second bundle size for the inter-CCE bundling may be configured as
a value for including a predetermined number of intra-CCE REG
bundle(s). For example, the second bundle size may be determined an
integer multiple of the first bundle size. For example, when the
intra-CCE bundling is performed in units of 2-REG (e.g., first
bundle size=2-REG) and the second bundle size for the inter-CCE
bundling is configured as 4-REG, a UE may assume the same precoding
with respect to 2 intra-CCE REG bundles (i.e., total of 4 REGs)
belonging to different CCEs and may perform channel estimation.
[0084] Alternatively, the UE may assume that a PRB bundle size
configured in a data (e.g., PDSCH) region is also applied to a
control channel. Such assumption may be applied to both cases in
which REGs present in a corresponding bundle size are contiguous or
noncontiguous and may also be applied to intra-CCE and/or
inter-CCE.
[0085] For example, assuming that 6-REG is mapped to 1 CCE via
localized mapping and 4-RB configures 1 bundle in the case of a
PDSCH, the intra-CCE REG bundle size or the inter-CCE bundle size
may be configured as 4. For example, assuming that 2 CCEs (e.g.,
CCE#0 and CCE#1) for an aggregation level (AL)-2 channel candidate
are contiguous in the frequency domain, REG bundling may be
performed according to [first bundle: 4-REG of CCE#0]+[second
bundle: 2-REG of CCE#0 & 2-REG of CCE#1]+[third bundle: 4-REG
of CCE#1].
[0086] To apply an REG bundle on the frequency domain, it may be
required to determine a boundary at which an REG bundle is
started/ended. For example, as described in (i) to (v), a boundary
of an REG bundle may be determined. When methods of (i) or (iv) is
used, it may be desirable to configure a bandwidth or PRB number
configured for a UE as a multiple of a bundle size.
[0087] (i) A bundle size may be applied from a lowest frequency
(e.g., lowest subcarrier) in a CORESET configured for a UE. For
example, REG indexing and/or REG bundle indexing may be used for
each CORESET and, when interleaving is used, interleaving may be
performed in units of REG bundles. When a reserved resource is
present in a bundle size or a PRB that is not allocated to a UE is
present, an actual bundle size of the UE may be smaller than a
bundle size indicated from a network.
[0088] (ii) A bundle size may be applied from a lowest frequency in
a UE-specific bandwidth configured for the UE. When a reserved
resource is present in a bundle size or a PRB that is not allocated
to the UE is present, an actual bundle size of the UE may be
smaller than a bundle size indicated from a network.
[0089] (iii) A bundle size may be applied from a lowest frequency
in an entire system bandwidth. When a reserved resource is present
in a bundle size or a PRB that is not allocated to the UE is
present, an actual bundle size of the UE may be smaller than a
bundle size indicated from a network.
[0090] (iv) The frequency domain to which an REG bundle is to be
applied may be separately configured and a bundle size may be
applied from a lowest frequency in the corresponding frequency
domain. When a reserved resource is present in a bundle size or a
PRB that is not allocated to the UE is present, an actual bundle
size of the UE may be smaller than a bundle size indicated from a
network.
[0091] (v) The UE may consider a starting point of a control
channel candidate as a position where REG bundling is started. For
example, a bundle size may be applied from a start CCE or start REG
of the candidate. The UE may assume that the same precoding is
applied to corresponding REGs when different REGs belonging to the
same candidate are present in a bundle size. When REGs belonging to
the candidate are distributed to different groups, the UE may
consider a starting point of each group as a starting point of a
bundle.
[0092] When a precoder cycling in which precoding is cyclically
changed every specific resource unit, or the like is used, bundling
may be performed in the same resource unit as the resource unit in
which the precoder cycling is applied. For example, assuming that 2
precoders are cyclically applied on contiguous REGs, even index
REGs may be bundled and odd index REGs may be bundled. This may be
understood as bundling at an REG group (e.g., even REG group/odd
REG group) level. For example, REGs to which Precoder 1 is applied
may correspond to a first REG group bundle and REGs to which
Precoder 2 is applied may correspond to a second REG group bundle.
In this case, even if precoder cycling is used, the UE may assume
the same precoding with respect to REGs belonging to the same
bundle.
[0093] When REG bundling and precoder cycling are used together,
the REG bundling may not be always performed on contiguous REGs.
For example, noncontiguous REGs may belong to the same REG bundle.
In this case, a UE may be allocated with an REG or RB bundle size
from a network and one or more precoders may be present in the
allocated REG/RB bundle size. The UE may be configured with the
number of precoders in the REG/RB bundle size from a network. The
number of precoders in the REG/RB bundle size may be different
according to a method of configuring precoder cycling. [0094]
Configuration of precoder cycling with REG/RB bundle size: For
example, to perform precoder cycling every RB/REG (e.g., to change
a precoder in units of RB/REGs), a network may configure a bundle
size as 1. [0095] Configuration of REG bundle along with
configuration of precoder cycling: A network may allocate an REG
bundle size and the number of precoders to be used in each bundle
to the UE. Assuming that 2 precoders cycle in a 6-RB bundle, the
network may perform precoder cycling in units of 1 REG/RB and, in
this case, 3 RBs may share the same precoder.
[0096] Time-Domain Bundling
[0097] Similarly to frequency domain bundling, the same precoding
may also be applied to REGs in a bundle size in the case of time
domain bundling.
[0098] According to a method of applying the same precoding, time
domain bundling may be differently defined. According to an
embodiment of the present invention, the time domain bundling may
be defined as two types as follows and a network may signal a type
of time domain bundling, to be used for each resource region (e.g.,
CORESET, sub-CORESET).
[0099] (1) Time Domain Bundling Type 1: When RS is Transmitted in
all REGs in Bundle
[0100] Type 1 bundling may be used to enhance channel estimation
performance. To enhance channel estimation, each of REGs in the
time domain bundle size may include an RS. Density of the RS may be
different for each REG. For example, density of an RS mapped to an
REG of a first OFDM symbol and density of an RS mapped to an REG of
a second OFDM symbol may be different.
[0101] As one of available operations of a UE with respect to Type
1 bundling, channel estimation may be performed using all RSs in a
bundle. For example, to obtain a channel coefficient of a specific
data RE through 2D-minimum mean square error (MMSE)-based channel
estimation, the UE may use all RSs in a bundle to which the
specific data RE belongs. In this case, similarly to the frequency
domain bundling, the UE may perform channel estimation using a
plurality of RSs to enhance channel estimation performance.
[0102] As another operation of a UE that performs Type 1 bundling,
the UE may performs channel estimation for each REG and, in this
case, may use an average of channel estimation results of REGs in a
bundle as a final channel estimation result. In this case, when
REGs in a bundle are present in a coherent time and channel
variation barely occurs, noise may be suppressed.
[0103] (2) Time Domain Bundling Type 2: When RS is Transmitted Only
in REG in Bundle (e.g., RS of Front-Loaded REG)
[0104] Type 2 bundling may be used as a method of reducing RS
overhead to acquire coding gain of control information. When Type 2
bundling is used, a network may transmit an RS only some REGs of
REGs in a bundle and may map control information to an RE position
from which an RS is omitted in the other REGs in which an RS is not
transmitted, thereby lowering a coding rate of the control
information.
[0105] In Type 2 bundling, a UE may perform channel estimation in
an REG in which an RS is transmitted and may reuse a channel
estimation result with respect to an REG in which an RS is not
transmitted. Such reuse of the channel estimation result may be
based on REG bundling definition for applying the same precoding to
REGs in a bundle.
[0106] FIG. 4 illustrates time domain bundling Types 1/2 according
to an embodiment of the present invention. R refers to an RE in
which an RS is transmitted and D refers to an RE in which control
information is transmitted. RSs of the same antenna port may be
mapped to all RS REs or RSs of different antenna ports may be
multiplexed and mapped using an FDM/CDM method.
[0107] As described above, time domain REG bundling may be defined
as Types 1/2 and a network may apply/signal different types of time
domain bundling for respective resource regions.
[0108] As another example, when a specific condition is satisfied,
application of a specific type of time domain bundling may also be
predefined.
[0109] FIG. 5 illustrates channel estimation performance of time
domain bundling according to an embodiment of the present
invention. The channel estimation performance illustrated in FIG. 5
is a result obtained under assumption that distributed mapping is
applied to a candidate of aggregation level 2 and indicates
performance when each type of time domain is applied to various
transport block sizes (TBSs).
[0110] A coding rate according to each type and each TBS in FIG. 5
may be (Type1, 36bits)=0.1875, (Type1, 76bits)=0.3958, (Type1,
100bits)=0.5208, (Type2, 36bits)=0.15, (Type2, 76bits)=0.3167, and
(Type2, 100bits)=0.4167.
[0111] Comparing the experimental result depending on a coding rate
with respect to each case, it may be seen that, when a coding rate
is high, time bundling of Type 2 is appropriate and, when a coding
rate is low, time bundling of Type 1 is appropriate.
[0112] In other words, when a coding rate is low, this means that
channel estimation performance largely affects overall performance
and, when a coding rate is high, coding gain largely affects
overall performance.
[0113] Based on the experimental result, a configuration of
different domain bundling types depending on a coding rate (e.g.,
for each aggregation level, for each DCI format, for each payload
size, and/or for each coding rate in consideration of reserved
resource) may be proposed. For example, a coding rate-specific time
bundling type may be defined. A time domain bundling type for each
aggregation level may be determined by a network or may be
determined for each DCI format or payload size.
[0114] To enhance system flexibility, a network/UE may divide
candidates in a resource region in which time domain bundling is
applied to distribute the candidates to time bundling types. For
example, when the UE needs to perform blind decoding on 4 AL-1
candidates, 4 AL-2 candidates, 2 AL-4 candidates, and 2 AL-8
candidates, the UE may perform blind decoding assuming Type 1 time
bundling with respect to a half of the candidates of each AL and
Type 2 time bundling with respect to the other half of the
candidate. For such an operation of the UE, a network may indicate
a candidate for which Type 1 needs to be assumed and a candidate
for which Type 2 needs to be assumed in a resource region in which
time domain bundling is performed, via higher layer signaling or
the like.
[0115] When an aggregation level of a candidate is differently
configured for each resource region (e.g., CORESET), a time domain
bundling type of a corresponding resource region may be determined
according to an aggregation level. For example, when CORESET 0 and
CORESET 1 are configured for a UE, only a candidate for ALs 1 and 2
is present in CORESET 0, and only a candidate for ALs 4 and 8 are
present in CORESET 1, the UE may perform blind decoding assuming
Type 2 time domain bundling with respect to CORESET 0 and Type 1
time domain bundling with respect to CORESET 1.
[0116] In addition, a type of time bundling may be determined
depending on speed of a UE. Type 1 time domain bundling is more
robust to a rapid channel change in the time domain than Type 2
time domain bundling. Based on speed, a Doppler frequency, or the
like of the UE, a time domain bundling type may also be determined.
To this end, the UE may periodically (or aperiodically) notify the
network about the speed, the Doppler frequency, or the like.
[0117] When time domain REG bundling and frequency domain REG
bundling are simultaneously applied, an RS configuration may be
determined according to a time domain REG bundling type. When only
the frequency domain REG bundling is applied, the RS may be
transmitted in all REGs or an REG in which the RS is transmitted
may be determined by a network.
[0118] Intra-CCE Bundling
[0119] Intra-CCE bundling may refer to bundling of REGs included in
1 CCE and, aforementioned time and/or frequency domain REG bundling
can be applied to the intra-CCE bundling.
[0120] For a specific resource region (e.g., CORESET), network may
indicate, to a UE via higher layer signaling etc., one of all or
some of options (i) to (iii) below or one of all or some of options
(i) to (iii) below may be predefined. For example, the network may
signal at least one of options (i) to (iii) to the UE through a
CORESET configuration.
[0121] (i) Whether time domain REG bundling is applied and/or
bundle size: Information indicating whether time domain REG
bundling is applied in a specific resource region and/or a bundle
size may be transmitted via network signaling etc., or may be
predefined. The information indicating whether the time domain REG
bundling is applied may be replaced with signaling of a bundle
size.
[0122] (ii) Whether frequency domain REG bundling is applied and/or
bundle size: Information indicating whether frequency domain REG
bundling is applied in a specific resource region and/or a bundle
size may be transmitted via network signaling etc., or may be
predefined. The information indicating whether the frequency domain
REG bundling is applied may be replaced with signaling of a bundle
size.
[0123] (iii) Whether time and frequency domain REG bundling is
applied and/or bundle size: Time domain REG bundling and frequency
domain REG bundling may be simultaneously applied. Information
indicating whether time and frequency domain REG bundling are
applied in a specific resource region may be transmitted via
network signaling etc., or may be predefined. The information
indicating whether the time and frequency domain REG bundling are
applied in the region may be replaced with signaling of a bundle
size for each domain.
[0124] A method of replacing the information indicating whether
time/frequency domain REG bundling is applied with signaling of a
bundle size is described now in more detail. When an REG bundle
size is equal to or greater than 2 REGs, it may be interpreted as
REG bundling is to be applied. In this case, whether the REG
bundling to be applied corresponds to time domain bundling,
frequency domain bundling, or time-frequency domain bundling may be
determined through a bundle size. For example, when a bundle size
of 2 or greater is configured in a specific resource region (e.g.,
CORESET) with duration of 1 symbol, it may be interpreted as
frequency domain REG bundling is to be applied. When a bundle size
is 2 in a specific resource region (e.g., CORESET) with duration of
2 symbols, it may be interpreted as time domain REG bundling is to
be applied and, when a bundle size is equal to or greater than 3
(e.g., bundle size=6), it may be interpreted as time-frequency
domain REG bundling is to be applied. When a bundle size is 3 in a
specific resource region (e.g., CORESET) with duration of 3
symbols, it may be interpreted as time domain REG bundling is to be
applied and, when a bundle size is equal to or greater than 4
(e.g., bundle size=6), it may be interpreted as time-frequency
domain REG bundling is to be applied.
[0125] More generally, assuming CORESET duration of N-symbol (N
being an integer equal to or greater than 2) and a bundle size of
M-REG, in the case of N.ltoreq.M, a UE may determine that time
domain bundling is applied to a corresponding CORESET and, in the
case of N>M, the UE may determine that time-frequency domain
bundling is applied to the corresponding CORESET. When CORESET
duration is 1 symbol, REG bundling may always refer to frequency
domain bundling and, in this case, a bundle size may also be
interpreted to be a size of frequency domain bundling.
[0126] FIG. 6 is a diagram showing bundling options according to an
embodiment of the present invention.
[0127] Referring to FIG. 6, (a) frequency bundling and (b) time
bundling illustrate the case in which a bundle size is 3. (c)
time-frequency bundling illustrates the case in which a bundle size
is 3 on the time domain and a bundle size is 2 on the frequency
domain. Accordingly, in the time-frequency bundling, 6 REGs may
configure one REG bundle.
[0128] In the case of intra-CCE bundling, a bundle size may also be
used as a basic unit of resource indexing. For example, when time
domain REG bundling is applied in a CORESET in which distributed
mapping is used, CORESET duration (i.e., length (symbol number) of
a CORESET in the time domain) may be replaced with a bundle size
and a bundle index may be used as a basic unit of distribution (or
interleaving). For example, an REG bundle size with the same size
as the CORESET duration may be supported. In addition, interleaving
may be performed in a unit of a REG bundle.
[0129] For example, when a specific CORESET is configured with a
combination of 100 PRBs & 3 symbols and time domain REG
bundling is applied to a specific CORESET, each PRB may be defined
to configure one bundle. For example, three contiguous REGs on the
time domain, which is positioned in the same frequency resource
(i.e., the same PRB) on the frequency domain, may correspond to one
REG bundle. In this case, a network may interleave a bundle index
of 0 to 99 in a logical domain and may perform mapping in a
physical domain.
[0130] Such a method may also be applied to the frequency domain in
the same way. For example, when a bundle size for frequency domain
REG bundling is signaled to 2 REGs, a UE may assume that two
contiguous REGs configure one bundle in the frequency domain and
may determine resource mapping or the like when performing blind
detection on a corresponding CORESET.
[0131] As described in the above embodiments, a size of time domain
REG bundling may be determined as a divisor of time domain duration
of a resource region (e.g., CORESET) in which bundling is applied.
For example, assuming four cases in which duration of a resource
region in which time domain bundling is applied is 1, 2, 3, and 4,
a combination of available time domain bundle sizes with respect to
each case may be (1), (1, 2), (1, 3), and (1, 2, 4). In other
words, in the case of resource region duration N=1, 2, 3 symbols,
time domain REG bundling may not be applied (i.e., bundle size=1),
or when time domain REG bundling is applied, a bundle size thereof
may be interpreted to be configured to be the same as duration N of
a resource region.
[0132] It may be desirable to configure a bundle size as a divisor
of duration of a resource region because, when the bundle size is
not configured as a divisor of duration of a resource region, the
possibility that different REGs use different frequency resources
in 1 bundle needs to be avoided. For example, when time domain
bundling is applied in a specific CORESET, bundle size=2 REGs, and
duration of a CORESET is 3 symbols, bundle 1 and bundle 3 among
bundles configured in a CORESET are positioned over different PRBs
and, thus, time domain bundling may not be capable of being
performed with respect to bundle 1 and bundle 3.
[0133] As another example of the present invention, in the case of
distributed resource mapping, only one of time/frequency domain REG
bundling may also be defined to be applied. For example, it may be
assumed that both time/frequency domain REG bundling are applied to
a CCE including 6 REGs, a time domain bundle size is 3, and a
frequency domain bundle size is 2. In this case, to easily perform
distribution for acquisition of frequency diversity, a network may
perform only REG bundling with respect to one domain.
[0134] In the case of localized resource mapping, application of
both time/frequency domains bundling or performing of only bundling
on one domain may be configured/predefined by a network. When both
time/frequency domain bundling are performed, one bundle in which
both bundling in two domains is applied may also be used as a basic
unit of resource indexing.
[0135] The above proposed resource region may be a CORESET or a
sub-CORESET included in the CORESET. sub-CORESETs may be
distinguished therebetween.
[0136] FIG. 7 illustrates a CORESET and a sub-CORESET according to
an embodiment of the present invention.
[0137] In (b) of FIG. 7, time domain REG bundling may not be
applied and only frequency domain REG bundling may be applied to
sub-CORESET0. Time domain REG bundling of bundle size 2 may be
applied to sub-CORESET1. Resource indexing may be independently
performed every subCORESET or may be performed on an entire CORESET
or a method for resource indexing may be indicated by a network via
higher layer signaling or the like.
[0138] FIG. 8 is a diagram for explanation of resource indexing
according to an embodiment of the present invention.
[0139] Referring to FIG. 8, (a) sub-CORESET separate indexing may
easily configure different search spaces and (b) resource indexing
(i.e., combined indexing) with respect to an entire CORESET may be
used as one method for simultaneously performing time/frequency
domain REG bundling. (a) separate indexing may also be used to
distinguish between a search space for DCI that needs to be rapidly
decoded and a search space for DCI with low limitation in decoding
time. Although FIG. 8 illustrates the case in which resource
indexing is performed from a first symbol using a frequency-first
method for convenience, a resource index may also be changed by
applying interleaving or the like.
[0140] Thus far, although bundling between contiguous REGs in the
time/frequency domain has been mainly described, time/frequency REG
bundling may be defined by a bundling pattern. For example, when a
bundling pattern is defined like {2, 1, 2, 1} for frequency domain
REG bundling, {REG0, REG1}, {REG2}, {REG3, REG4}, and {REG5} among
6 REGs configuring one CCE may each configure an REG bundle.
[0141] The bundling pattern may also be used in time domain REG
bundling. For example, when duration of a resource region in which
time domain REG bundling is applied is 3 symbols, a network may
signal a bundling pattern of {2, 1}. A bundling pattern {2, 1} may
mean that 2 contiguous REGs configure on bundle and one subsequent
REG configures another bundle in the time domain. Time bundling
Type 1/2 for each bundle included in the pattern may be predefined
or may be signaled by the above proposed method.
[0142] Inter-CCE Bundling
[0143] Like intra-CCE bundling, in the case of inter-CCE bundling,
whether bundling is applied and/or a bundle size may also be
signaled by a network. The aforementioned REG level bundling
related proposals may also be applied to CCE level bundling and, in
the above proposals, an REG may be replaced with a CCE and
inter-CCE bundling may be embodied.
[0144] When inter-CCE bundling is embodied using the aforementioned
method, there may be additional limitation in a procedure such as
resource indexing. For example, assuming that the inter-CCE
bundling is always applied, an inter-CCE bundle size may need to be
assumed and CCE indexing may need to be performed. For example,
even if CCE indexes are contiguous, the inter-CCE bundling may need
to be performed on different CCEs with noncontiguous time/frequency
positions and, thus, CCE indexing may be performed in consideration
of a bundle size.
[0145] Accordingly, to apply the inter-CCE bundling, a network may
configure only whether the inter-CCE bundling is applied and a
bundle size and, when the inter-CCE bundling is applied, a UE may
assume the same precoding to be applied when contiguous resources
are present in the bundle size in the time/frequency domain.
[0146] A bundle size for the inter-CCE bundling may be independent
from an intra-CCE bundle size. Alternatively, when a maximum bundle
size for the inter-CCE bundling is separately defined and REGs
belonging to different CCEs are adjacent to each other, assumption
of the same precoding in a maximum bundle size by a UE may be
predefined or may be signaled by a network.
[0147] In addition, inter-CCE bundling in a CORESET to which
interleaving is applied may be replaced with a configuration of an
interleaving unit size. To effectively configure a hierarchical
PDDCH structure and/or to reduce blocking probability between
CORESETs, interleaving of an REG bundle set unit may be introduced.
For example, a network may contiguously deploy REGs belonging to
each CCE configuring a candidate with a high aggregation level in a
CORESET to which interleaving is applied and may interleave an REG
bundle set. When REG bundle set-based interleaving is performed and
a size of an REG bundle set is configured (for each CORESET), a UE
may assume that the size of the REG bundle set is the same as an
inter-CCE REG bundle size.
[0148] For example, when REG {0, 1, 2, 3, 4, 5} configures CCE0 and
REG {6, 7, 8, 9, 10, 11} configures CCE1 in 1 symbol CORESET in
which interleaving is performed, and CCE0 and CCE1 configure a
candidate with aggregation level 2, a network may pair an REG
configuring each CCE one by one and may perform interleaving. For
example, REG {0, 6}, {1, 7}, {2, 8}, {3, 9}, {4, 10}, and {5, 11}
may be used in units of interleaving.
[0149] <Wideband Reference Signal>
[0150] To enhance system flexibility in NR, a method of reducing a
common RS and an operation in terms of a UE-specific demodulation
reference signal (DMRS) has been discussed. However, a wideband RS
may be periodically transmitted for the purpose of channel
estimation performance and measurement of a control channel, phase
tracking, and so on. When the wideband RS is used, the number of
RSs to be used by a UE during channel estimation may be increased
to enhance channel estimation performance. In addition, the UE may
perform wideband RS cell or beam level measurement to more
effectively perform a procedure such as a cell change and a beam
change.
[0151] A UE-dedicated beamforming method, a transmission diversity
method, or the like may be applied to a control channel of NR to
transmit control information and, a wideband RS may be more
appropriate for the transmission diversity method. In the
UE-dedicated beamforming method, precoding for maximizing a
reception SNR depending on a channel situation of each UE may be
applied and, thus, may be more appropriate for a narrowband
operation. Accordingly, use of the transmission diversity method
may be more appropriate in a resource region in which the wideband
RS is applied.
[0152] In NR, a scheme such as 2-Port space frequency block coding
(SFBC), 1-Port RB level precoder cycling, and 1-Port stacked cyclic
delay diversity (SCDD) may be used as the transmission diversity
method. The 1-port RB level precoder cycling may have excellent
performance at a high AL and may disadvantageously enable decoding
using the same operation as UE-dedicated beamforming in terms of a
UE. However, to apply the wideband RS to the 1-port RB level
precoder cycling scheme, additional signaling may be required.
[0153] A UE may assume that the same precoder is used in a region
in which the wideband RS is transmitted and, thus, may perform
channel estimation using all RSs in the corresponding region and
may perform measurement, tracking, or the like. On the other hand,
1-port RB level precoder cycling may be a method for acquisition of
beam diversity gain using different precoders for RBs. Accordingly,
to simultaneously apply the precoder cycling scheme and the
wideband RS, the following information elements need to be
signaled. The following information elements may be indicated via
higher layer signaling or the like or may be signaled in an initial
access procedure. All or some of the following information elements
may be signaled to a UE and, when only some of the following
information elements, non-signaled information elements may be
predefined.
[0154] (i) Period of Wideband RS
[0155] A period with which a wideband RS is transmitted, a subframe
set, or the like may be indicated to the UE via higher layer
signaling or the like. The UE may perform control channel decoding
based on the wideband RS in a slot in which the wideband RS is
transmitted.
[0156] (ii) Transmission Region of Wideband RS
[0157] The time/the frequency domain in a slot in the wideband RS
is transmitted may be signaled. The frequency domain of the
wideband RS may be signaled in units of multiples of a UE minimum
bandwidth (i.e., a minimum BW specified in NR) and a starting point
or the like of the wideband RS may be additionally signaled. A
symbol (or symbol set) in which the wideband RS is transmitted may
also be signaled as the time domain of the wideband RS.
[0158] As another method, a transmission region of the wideband RS
may be signaled in units of CORESETs (or subCORESETs). For example,
the transmission region of the wideband RS may be signaled using a
method of adding whether the wideband RS is transmitted or the like
to a CORESET configuration. For example, as shown in (b) of FIG. 7,
when a subCORESET is configured and a wideband RS is applied only
to subCORESET0, a different precoder from a precoder of subCORESET0
in which the wideband RS is transmitted may be applied to an REG
(or REG bundle) of subCORESET1.
[0159] (iii) The Same Precoding Pattern in Wideband
[0160] As described above, when the 1-port RB level precoder
cycling is used, a precoder may be changed for each RB or RB group.
Accordingly, an eNB may signal an RB pattern or the like to which
the same precoder is applied among regions in which the wideband RS
is transmitted. For example, a network may notify a UE about
precoding information in a resource region in which the wideband RS
is applied.
[0161] Although FIG. 9 below exemplifies a method of transmitting
precoding information to a UE using a concept of a pattern, a
sub-pattern, or the like, the present invention is not limited
thereto and precoding information may be transmitted using various
methods. To reduce signaling overhead or the like, at least some of
the following precoding information items may be predefined. For
example, a precoding related pattern in a resource region in which
the wideband RS is used may be predefined. For example, the
precoding related pattern may be defined using the following
proposed pattern and sub-pattern, and so on.
[0162] FIG. 9 is a diagram for explanation of a method of
indicating the same precoding pattern according to an embodiment of
the present invention. In FIG. 9, the same numeral may refer to
application of the same precoding.
[0163] When 1-port RB level precoder cycling is used, a network may
signal a pattern length, a sub-pattern length, and the like to
notify a UE about sections in which the same precoding is applied.
Here, the pattern may refer to a precoder cycling period and the
sub-pattern may refer to resource sections in which the same
precoding is applied.
[0164] For example, in (a) of FIG. 9, a network may signal a
pattern length of 6 and a sub-pattern length of 2 to a UE. The UE
may apply the pattern and the sub-pattern to a section in which the
wideband RS is applied to identify resources to which the same
precoding is applied and may perform channel estimation,
measurement, tracking, and so on based on the corresponding
resource.
[0165] (b) of FIG. 9 illustrates another example of application of
a wideband RS. As shown in (b) of FIG. 9, when the wideband RS is
transmitted, this may be effective to perform measurement for each
section. When REG/REG bundles configuring a CCE or different CCEs
configuring a candidate are distributed in different sub-patterns,
a valid bundle size may be relatively increased and, thus,
frequency diversity gain may be obtained and channel estimation
performance may also be enhanced.
[0166] <Configurable RS Density>
[0167] With regard to the RS mapping methods proposed in FIG. 4,
(a) Type 1 may be referred to as a full loaded RS method, (b) Type
2 may be referred to as a front loaded RS method, and the front
loaded RS method may advantageously ensure a lower coding rate for
a control signal than the full loaded RS method.
[0168] In addition, a method of lowering a coding rate in the full
loaded RS method may be proposed. For example, to lower a coding
rate, RS density may be adjusted based on channel estimation
performance.
[0169] FIG. 10 illustrates RS patterns for adjusting RS density
according to an embodiment of the present invention. In FIG. 10, an
RS pattern (i.e., a position of an RE in which an RS is
transmitted) may be changed. For example, an RS may be mapped as
shown in FIG. 4.
[0170] Referring to FIG. 10, RS density may be differently
configured according to each RS pattern. Accordingly, the number of
data REs for transmission of control information may also be
differently configured according to each RS pattern. All or some of
3 RS patterns may be defined for an NR control channel.
[0171] A network may configure an RS pattern with relatively low
density for a UE with an excellent channel environment or a UE (or
a UE group), channel estimation performance of which is ensured.
For example, an RS pattern to be assumed by a UE in a corresponding
CORESET for each CORESET may be configured. The UE may assume an RS
pattern in the corresponding CORESET according to an RS
configuration for each CORESET.
[0172] An RS pattern to be assumed by a UE in each CORESET may be
determined in association with CORESET duration (without additional
signaling). For example, when configurable CORESET duration is 1,
2, and 3 symbols, a UE may assume that RS patterns are used in
respective durations. When CORESET duration is 1, (a) 1/3 RS
pattern may be used, when CORESET duration is 2, 1/4 RS pattern may
be used, and when CORESET duration is 3, use of 1/6 RS pattern may
be configured/predefined.
[0173] Application of such association between CORESET duration and
an RS pattern may be determined according to whether time domain
bundling is performed. For example, in the case of a CORESET to
which time domain bundling (e.g., a UE may assume that the same
precoding is applied to REGs belonging to the same bundle in the
time domain) is applied, a predetermined RS pattern may be used
according to CORESET duration. When the time domain bundling is not
applied, only a specific RS pattern (e.g., 1/3 RS pattern) may be
predefined to be used irrespective of CORESET duration. This is
because, when the time domain bundling is applied, channel
estimation performance is enhanced compared with time domain
bundling and, thus, even if RS density per REG is lowered, channel
estimation performance is not largely degraded.
[0174] Through such a method, additional coding gain may be
obtained while channel estimation performance is ensured. For
example, when an RS pattern with low density is used, a similar
effect to Type 2 of FIG. 4 may be expected.
[0175] An RS pattern to be assumed by a UE in each CORESET may be
determined in association with a bundling option of each CORESET
(without additional signaling). REG bundling may be possible with
respect to NR-PDCCH in the time/frequency domain and performance
enhancement may be expected via REG bundling in terms of channel
estimation. As such, when sufficient channel estimation performance
is capable of being obtained via REG bundling, it may be desirable
to lower RS density to acquire gain in terms of a coding rate.
[0176] Accordingly, according to an embodiment of the present
invention, RS density may be determined in association with a whole
bundle size. For example, in the time/frequency domain, a bundle
size may be represented according to (Time, Frequency)=(1, 6), (2,
3), (3, 2), (2, 1), (3, 1) (where, in the case of 1 symbol CORESET,
(1, 2) and (1, 3) are also possible) and, when the sum of bundle
sizes of the time and frequency domains is equal to or greater than
5, an RS pattern corresponding to RS density of 1/6 may be used. On
the other hand, when the sum of bundle sizes in the time and
frequency domains is less than 5, an RS pattern corresponding to RS
density of 1/3 may be applied.
[0177] As another example, when time domain bundling is used for
the purpose of reducing of a coding rate (e.g., an RS is
transmitted only to some of REGs of the time domain bundle), RS
density may be determined based on a frequency domain bundle size.
For example, the frequency domain bundle size is greater than 2
REGs, an RS pattern corresponding to RS density of 1/6 may be used
and, when the frequency domain bundle size is 1 or 2, an RS pattern
corresponding to RS density of 1/3 and 1/4 may be used.
[0178] The above proposed configurable RS pattern (or CORESET
duration-based RS pattern) may enhance efficiency in terms of
channel estimation performance and a coding rate but an operating
method for the case in which CORESETs with different CORESET
durations overlap with each other needs to be defined.
[0179] FIG. 11 illustrates the case in which CORESETs with
different CORESET durations overlap with each other according to an
embodiment of the present invention.
[0180] Referring to FIG. 11, CORESET 0 of Duration 1 and CORESET 1
of Duration 3 may partially overlap with each other. It may be
assumed that 1/3 RS pattern is used in CORESET0 and time domain
bundling is applied and 1/6 RS pattern is used in CORESET1 (e.g., a
bundle size: 1 in the frequency domain & 3 in the time domain).
In this case, an RS pattern is redundantly configured in Region0
and, thus, when how an RS patterns is processed in Region 0 is not
defined, there may be a problem in that a UE wrongly refers to an
RS during blind decoding of the UE as well as channel estimation or
decoding performance is degraded.
[0181] To overcome a problem that arises when RS patterns are
configured to overlap with each other in the time/frequency domain
due to overlap between different CORESETs, the following methods
(i) to (iv) are proposed. A specific option among the following
options may be predefined to be used when CORESETs overlap with
each other or may be configured for a UE by a network. In addition,
the following options may also be applied when CORESETs overlap
with each other irrespective of an RS pattern (e.g., even when RS
patterns of different CORESETs are the same).
[0182] (i) Option 1: Assumption of Only RS Pattern of Corresponding
CORESET
[0183] For an NR-PDCCH, a UE-specific DMRS may be basically used.
Accordingly, a UE may assume only an RS pattern of a corresponding
CORESET while performing blind decoding on a control channel
candidate that belongs to a specific CORESET. For an operation such
as Option 1, it may be assumed that a network does not transmit
different PDCCHs to the same resource using the same RS portion.
For example, it may be assumed that an RS pattern configured in
CORESET1 is always used in Regions 1 and 2 in FIG. 11. The UE may
assume that only an RS pattern of CORESET0 is present while
performing blind decoding on a candidate of CORESET0 in Region 0,
may assume that only an RS pattern of CORESET1 while performing
blind decoding on a candidate of CORESET1 in Region 0, and may
perform blind decoding.
[0184] (ii) Option 2: Change in RS Pattern
[0185] When a plurality of CORESETs are configured for one UE and a
section in which CORESETs overlap with each other in the
time/frequency domain is present, an RS pattern of a specific
CORESET may be changed in all CORESETs or a section in which the
CORESETs overlap with each other. To this end, a network may
configure RS pattern information (e.g., v-shift information
indicating frequency shift) of a corresponding CORESET together
while configuring a CORESET.
[0186] Alternatively, a UE may assume that an RS pattern of a
specific CORESET is changed to a predefined pattern when CORESETs
overlap with each other without signaling of a network.
[0187] To this end, priority between CORESETs may be defined and an
RS pattern of a CORESET with low priority may be changed. A CORESET
with high priority may be, for example, a CORESET in which an RS
(e.g., wideband RS) transmitted irrespective of whether a PDCCH is
transmitted and a UE may assume that an RS pattern of such a
CORESET is not changed.
[0188] When an RS pattern is changed to a predefined pattern, the
predefined pattern may be defined through, for example, a v-shift
value (e.g., a position of an RS is moved by a v-shift value in the
frequency domain).
[0189] (iii) Option 3: Rate-Matching of Different CORESET
[0190] It may be assumed that an RS (e.g., Wideband RS) transmitted
irrespective of whether a PDCCH is transmitted is transmitted in a
specific CORESET (or specific time/the frequency domain) and that
another CORESET that overleaps with the corresponding CORESET is
configured. In this case, a UE may assume that RS pattern positions
of different CORESETs are rate-matched in mapping of control
information while performing blind decoding on each CORESET.
[0191] In this case, since control information is rate-matched with
respect to an RS pattern position, a coding rate of the control
information may be increased and, as a result, decoding performance
of the UE may be degraded. When RS patterns are redundantly
configured in the same time/frequency resource, an RS may not be
frequently used in a corresponding region. For example, when 1/3 RS
pattern and 1/6 RS pattern of FIG. 10 are used in different
CORESETs, respectively, RS REs according to the 1/6 RS pattern may
be redundantly configured as RS REs according to the 1/3
pattern.
[0192] To overcome this problem, when Option 3 is used, an RS
pattern needs to be determined in such a way that RS RE positions
are not redundant between RS patterns. To prevent an RE in which an
RS is transmitted from being redundant, the method of changing an
RS pattern configured in Option 2 may also be used.
[0193] (iv) Option 4: Use of RS Pattern of CORESET with High
Priority
[0194] When an RS (e.g., wideband RS) transmitted irrespective of
whether a PDCCH is transmitted in a specific CORESET (or specific
time/the frequency domain) and another CORESET that overlaps with
the corresponding CORESET is configured, a UE may assume only an RS
pattern of a CORESET with high priority in a section (e.g., region
0 of FIG. 11) in which CORESETs overlap with each other while
performing blind decoding on each CORESET. For example, the UE may
assume that an RS pattern defined in a CORESET with low priority is
not used in a section in which CORESETs overleap with each
other.
[0195] Priority of CORESETs may be configured by a network or may
be predefined. When the priority of CORESETs is predefined, high
priority may be assigned to a CORESET including a common search
space, a CORESET in which a wideband RS (e.g., RSs that are
transmitted at a time interval in a predetermined region
irrespective of whether a PDCCH is transmitted) is transmitted, or
the like.
[0196] When a CORESET in which a wideband RS is transmitted and a
CORESET in which a DMRS is transmitted entirely or partially
overlap with each other (e.g., when a wideband RS is used in
CORESET 0 and a DMRS is used in CORESET1 in FIG. 11) and Option 3
or Option 4 is used, even if time domain bundling is applied to
CORESET1, a UE may separately perform channel estimation with
respect to each of Region0 and Region1. For example, the UE may
apply the channel estimation result using the wideband RS to a
corresponding REG in Region0 and may apply the channel estimation
result using the DMRS to the corresponding to REG in Region1. In
this case, the UE may assume that time domain bundling is applied
only to Region1. A time domain bundle size in a region in which
CORESETs overlap with each other may be interpreted to be different
from a bundle size of a corresponding CORESET. Time domain bundling
may be determined according to a configuration of a CORESET in
Region2.
[0197] FIG. 12 illustrates a flow of a method of transmitting and
receiving downlink control information (DCI) according to an
embodiment of the present invention. FIG. 12 illustrates an example
of the aforementioned methods and the present invention is not
limited to FIG. 12 and, thus, a repeated description of the above
description may not be given here.
[0198] Referring to FIG. 12, an eNB may transmit bundling
information on resource element groups (REGs) via higher layer
signaling (1205). Each REG may correspond to 1 resource block (RB)
and 1 orthogonal frequency divisional multiplexing (OFDM) symbol.
The eNB may transmit bundling information via higher layer
signaling of a CORESET configuration.
[0199] One or more CORESETs may be configured in one UE. For
example, an eNB may transmit one or more or more CORESET
configurations to one UE to configure one or more CORESETs.
Bundling information and a control channel element (CCE)-to-REG
mapping type may be indicated (e.g., indicated though a CORESET
configuration) for each CORESET. The bundling information may
include bundle size information indicating the number of REGs
included in 1 REG bundle. The CCE-to-REG mapping type of a CORESET
may indicate one of a localized mapping type (e.g., non-interleaved
mapping) and an interleaved mapping type.
[0200] Hereinafter, for convenience of description, a CCE-to-REG
mapping type of a CORESET is assumed to be configured as an
interleaving mapping type. In addition, a CORESET may be assumed to
be configured on a plurality of OFDM symbols. For example, the
number of a plurality of OFDM symbols for configuring a CORESET may
be 2 or 3.
[0201] The eNB may generate DL control information (DCI)
(1210).
[0202] The eNB may transmit the generated DCI through a PDCCH
(1215).
[0203] When bundling information indicates a first value, the eNB
may perform bundling such that only REGs locating on a same RB and
corresponding to different OFDM symbols in the CORESET, are bundled
as 1 REG bundle. When the bundling information indicates a second
value, the eNB may perform bundling such that the REGs locating on
the same RB and corresponding to the different OFDM symbols are
bundled as 1 REG bundle along with REGs locating on different RBs
in the CORESET. The eNB may transmit the DCI by applying same
precoding for REGs belonging to a same REG bundle as a result of
REG bundling.
[0204] The UE may perform blind detection for a physical downlink
control channel (PDCCH) in a control resource set (CORESET)
configured on a plurality of OFDM symbols (1220).
[0205] The UE may acquire DL control information (DCI) from the
blind-detected PDCCH (1225). When the bundling information
indicates a first value, the UE may perform bundling such that only
REGs locating on a same RB and corresponding to different OFDM
symbols in the CORESET, are bundled as 1 REG bundle. When the
bundling information indicates a second value, the UE may perform
bundling such that the REGs locating on the same RB and
corresponding to the different OFDM symbols are bundled as 1 REG
bundle along with REGs locating on different RBs in the CORESET.
For example, when the bundling information indicates the first
value, the UE may perform time domain REG bundling and, when the
bundling information indicates the second value, the UE may perform
time-frequency domain REG bundling.
[0206] The UE may perform the blind detection for the PDCCH by
assuming same precoding for REGs which belong to a same REG bundle
as a result of REG bundling. For example, the UE may perform
demodulation for the PDCCH by assuming that the same precoding is
applied to RSs received through REGs belonging to the same REG
bundle and.
[0207] When the bundling information indicates the first value, 1
REG bundle size may be configured to be the same as the number of
the plurality of OFDM symbols for configuring a CORESET.
[0208] When the bundling information indicates the second value, 1
REG bundle size may be configured to be the same as the number of
REGs included in 1 control channel element (CCE).
[0209] Interleaving for CCE-to-REG mapping may be performed in a
unit of a REG bundle using an REG bundle index.
[0210] A supported bundle size may be determined according to a
CCE-to-REG mapping type.
[0211] For example, bundling information may include at least one
of intra-CCE bundle size information for bundling of REGs belonging
to the same control channel element (CCE) and inter-CCE bundle size
information for bundling of REGs belonging to different control
channel elements (CCEs). When the bundling information includes the
inter-CCE bundle size information, the UE may perform blind
detection for the PDCCH by assuming the same precoding with respect
to REGs of different CCEs belonging to the same inter-CCE
bundle.
[0212] FIG. 13 is a block diagram illustrating a structure of a
base station (BS) 105 and a UE 110 in a wireless communication
system 100 according to an embodiment of the present invention. The
structure of the BS 105 and the UE 110 of FIG. 13 are merely an
embodiment of a BS and a UE for implementing the aforementioned
method and the structure of a BS and a UE according to the present
invention is not limited to FIG. 13. The BS 105 may also be
referred to as an eNB or a gNB. The UE 110 may also be referred to
as a user terminal.
[0213] Although one BS 105 and one UE 110 are illustrated for
simplifying the wireless communication system 100, the wireless
communication system 100 may include one or more BSs and/or one or
more UEs.
[0214] The BS 105 may include a transmission (Tx) data processor
115, a symbol modulator 120, a transmitter 125, a
transmission/reception antenna 130, a processor 180, a memory 185,
a receiver 190, a symbol demodulator 195, and a reception (Rx) data
processor 197. The UE 110 may include a Tx data processor 165, a
symbol modulator 170, a transmitter 175, a transmission/reception
antenna 135, a processor 155, a memory 160, a receiver 140, a
symbol demodulator 155, and an Rx data processor 150. In FIG. 12,
although one antenna 130 is used for the BS 105 and one antenna 135
is used for the UE 110, each of the BS 105 and the UE 110 may also
include a plurality of antennas as necessary. Therefore, the BS 105
and the UE 110 according to the present invention support a
Multiple Input Multiple Output (MIMO) system. The BS 105 according
to the present invention can support both a Single User-MIMO
(SU-MIMO) scheme and a Multi User-MIMO (MU-MIMO) scheme.
[0215] In downlink, the Tx data processor 115 receives traffic
data, formats the received traffic data, codes the formatted
traffic data, interleaves the coded traffic data, and modulates the
interleaved data (or performs symbol mapping upon the interleaved
data), such that it provides modulation symbols (i.e., data
symbols). The symbol modulator 120 receives and processes the data
symbols and pilot symbols, such that it provides a stream of
symbols.
[0216] The symbol modulator 120 multiplexes data and pilot symbols,
and transmits the multiplexed data and pilot symbols to the
transmitter 125. In this case, each transmission (Tx) symbol may be
a data symbol, a pilot symbol, or a value of a zero signal (null
signal). In each symbol period, pilot symbols may be successively
transmitted during each symbol period. The pilot symbols may be an
FDM symbol, an OFDM symbol, a Time Division Multiplexing (TDM)
symbol, or a Code Division Multiplexing (CDM) symbol.
[0217] The transmitter 125 receives a stream of symbols, converts
the received symbols into one or more analog signals, and
additionally adjusts the one or more analog signals (e.g.,
amplification, filtering, and frequency upconversion of the analog
signals), such that it generates a downlink signal appropriate for
data transmission through an RF channel. Subsequently, the downlink
signal is transmitted to the UE through the antenna 130.
[0218] Configuration of the UE 110 will hereinafter be described in
detail. The antenna 135 of the UE 110 receives a DL signal from the
BS 105, and transmits the DL signal to the receiver 140. The
receiver 140 performs adjustment (e.g., filtering, amplification,
and frequency downconversion) of the received DL signal, and
digitizes the adjusted signal to obtain samples. The symbol
demodulator 145 demodulates the received pilot symbols, and
provides the demodulated result to the processor 155 to perform
channel estimation.
[0219] The symbol demodulator 145 receives a frequency response
estimation value for downlink from the processor 155, demodulates
the received data symbols, obtains data symbol estimation values
(indicating estimation values of the transmitted data symbols), and
provides the data symbol estimation values to the Rx data processor
150. The Rx data processor 150 performs demodulation (i.e.,
symbol-demapping) of data symbol estimation values, deinterleaves
the demodulated result, decodes the deinterleaved result, and
recovers the transmitted traffic data.
[0220] The processing of the symbol demodulator 145 and the Rx data
processor 150 is complementary to that of the symbol modulator 120
and the Tx data processor 115 in the BS 205.
[0221] The Tx data processor 165 of the UE 110 processes traffic
data in uplink, and provides data symbols. The symbol modulator 170
receives and multiplexes data symbols, and modulates the
multiplexed data symbols, such that it can provide a stream of
symbols to the transmitter 175. The transmitter 175 obtains and
processes the stream of symbols to generate an uplink (UL) signal,
and the UL signal is transmitted to the BS 105 through the antenna
135. The transmitter and the receiver of UE/BS can be implemented
as a single radio frequency (RF) unit.
[0222] The BS 105 receives the UL signal from the UE 110 through
the antenna 130. The receiver processes the received UL signal to
obtain samples. Subsequently, the symbol demodulator 195 processes
the symbols, and provides pilot symbols and data symbol estimation
values received via uplink. The Rx data processor 197 processes the
data symbol estimation value, and recovers traffic data received
from the UE 110.
[0223] A processor 155 or 180 of the UE 110 or the BS 105 commands
or indicates operations of the UE 110 or the BS 105. For example,
the processor 155 or 180 of the UE 110 or the BS 105 controls,
adjusts, and manages operations of the UE 210 or the BS 105. Each
processor 155 or 180 may be connected to a memory unit 160 or 185
for storing program code and data. The memory 160 or 185 is
connected to the processor 155 or 180, such that it can store the
operating system, applications, and general files.
[0224] The processor 155 or 180 may also be referred to as a
controller, a microcontroller), a microprocessor, a microcomputer,
etc. In the meantime, the processor 155 or 180 may be implemented
by various means, for example, hardware, firmware, software, or a
combination thereof. In a hardware configuration, methods according
to the embodiments of the present invention may be implemented by
the processor 155 or 180, for example, one or more application
specific integrated circuits (ASICs), digital signal processors
(DSPs), digital signal processing devices (DSPDs), programmable
logic devices (PLDs), field programmable gate arrays (FPGAs),
processors, controllers, microcontrollers, microprocessors,
etc.
[0225] In a firmware or software configuration, methods according
to the embodiments of the present invention may be implemented in
the form of modules, procedures, functions, etc. which perform the
above-described functions or operations. Firmware or software
implemented in the present invention may be contained in the
processor 155 or 180 or the memory unit 160 or 185, such that it
can be driven by the processor 155 or 180.
[0226] Radio interface protocol layers among the UE 110, the BS
105, and a wireless communication system (i.e., network) can be
classified into a first layer (L1 layer), a second layer (L2 layer)
and a third layer (L3 layer) on the basis of the lower three layers
of the Open System Interconnection (OSI) reference model widely
known in communication systems. A physical layer belonging to the
first layer (L1) provides an information transfer service through a
physical channel. A Radio Resource Control (RRC) layer belonging to
the third layer (L3) controls radio resources between the UE and
the network. The UE 110 and the BS 105 may exchange RRC messages
with each other through the wireless communication network and the
RRC layer.
[0227] The above-mentioned embodiments correspond to combinations
of elements and features of the present invention in prescribed
forms. And, it is able to consider that the respective elements or
features are selective unless they are explicitly mentioned. Each
of the elements or features can be implemented in a form failing to
be combined with other elements or features. Moreover, it is able
to implement an embodiment of the present invention by combining
elements and/or features together in part. A sequence of operations
explained for each embodiment of the present invention can be
modified. Some configurations or features of one embodiment can be
included in another embodiment or can be substituted for
corresponding configurations or features of another embodiment.
And, it is apparently understandable that an embodiment is
configured by combining claims failing to have relation of explicit
citation in the appended claims together or can be included as new
claims by amendment after filing an application.
[0228] While the present invention has been described and
illustrated herein with reference to the preferred embodiments
thereof, it will be apparent to those skilled in the art that
various modifications and variations can be made therein without
departing from the spirit and scope of the invention. Thus, it is
intended that the present invention covers the modifications and
variations of this invention that come within the scope of the
appended claims and their equivalents.
INDUSTRIAL APPLICABILITY
[0229] As described above, the present invention may be applied to
various wireless communication systems.
* * * * *